When purchasing a processor or desktop computer, you often look at the clock speed. Calculated in megahertz and gigahertz, or MHz and GHz, these measurements only tell one small part of the story of your central processing unit, or CPU. In addition to understanding the clock speed, modern CPU measuring tools also look at other factors in getting an idea of how well a processor performs.

Clock Frequency Explained

The most widely used metric for comparing processors is the clock frequency. A 2GHz processor, for example, would be regarded as faster than a 2.5GHz processor. When the two processors are fully taxed, in theory, then each second the higher-clock-rate processor will take care of 500 million more bits of data than the slower-clock-rate processor. The clock is set using a small quartz crystal, and can often vary based on how efficient a cooling system you have. Running a processor at a higher clock speed that than that for which it was designed is a common practice called “overclocking.” But the hertz only measure the literal number of signals that can be pushed through the processor in a single second, while the actual processing is much more complicated.

Instructions Per Second

In short, clock frequencies say little about how fast a CPU functions. When measuring a CPU, many experts attempt to read the millions of instructions per second, or MIPS. MIPS looks at how many instructions can make it through the “pipeline” of a processor, from receiving the instruction to fully processing its result. While a MIPS measurement provides a closer look at how a processor performs, it can still be a misleading measure of how fast your processor can execute code. This is due to optimizing enhancements found in many processors which MIPS measurement tools often don’t use, such as separate floating point processors.

Multi-Core Processing

Modern processors come in packages with multiple “cores.” The cores each have their own set of processing capabilities, allowing instructions to be processed simultaneously. A quad-core 2.8GHz means that there are four separate 2.8GHz processors functioning in the same package as a single-core 2.8GHz processor. The number of cores has, therefore, become yet another important measure of performance.

Other Factors

Just before the end of its product life, the Pentium 4 line of processors had reached a clock speed of 3.8GHz; meanwhile, its successor only recently reached that same clock-speed mark. The arguable increase in performance, in spite of the stagnation of the clock speeds, comes from other innovations. The Pentium 4, for example, had a 21-stage pipeline. This means that any instruction had to pass all 21 stages, and any failures or redirections would result in a restart of the 21-stage process. The new processor, by contrast, has fewer stages to its processing pipeline. This means that the newer processor handles instructions more efficiently. Furthermore, different processors carry different levels of processing cache. A higher cache allows a processor to quickly access frequently used instructions and better mitigate page faults. As a result, comparably measured processors with bigger cache sizes will often perform better.

CPU Speed Measurement Programs

Quality consumer CPU-measuring programs, also referred to as benchmark programs, measure a number of different factors. You have to take these factors in aggregate to get a good idea of how your CPU measures up. To this end, these benchmarking programs often return a custom scoring value for a variety of tests. The aggregate score may be viewed alongside scores relating to specific functions. For example, the software may measure both the single-core performance in a processor and the performance when taxing all cores simultaneously. These individual and aggregate scores can then be compared to other CPUs run through the same benchmark program to give a relative idea of the CPU’s actual performance.

About the Author

Jacob Andrew previously worked as an A+ and CCNA-certified technology specialist. After receiving his BA in journalism from the University of Wisconsin, Madison in 2012, he turned his focus towards writing about travel, politics and current technology.